The Blues made the Cup Final in each of their first three seasons, when the NHL doubled to 12 teams, the expansion teams had their own division and one was guaranteed to make the Cup Final. The Blues were swept by the Montreal Canadiens in 1968 and 1969 and by the Bruins in 1970.
Four of the other expansion teams from 1967-68 have won the Cup since, three multiple times. The Philadelphia Flyers won it in 1974 and 1975. The Pittsburgh Penguins won it in 1991 and 1992. The Minnesota North Stars moved to Dallas in 1993, dropped the "North" from their name and won it in 1999. The Penguins won it in 2009. The Los Angeles Kings won it in 2012 and 2014. The Penguins won it twice more, in 2016 and 2017.
The Oakland Seals became the California Golden Seals in 1970, became the Cleveland Barons in 1976 and merged with the North Stars in 1978. The Blues didn't return to the Cup Final until this season despite winning consistently with great players like Bernie Federko and Brett Hull and Al MacInnis, whose statues stand outside Enterprise Center. Even Wayne Gretzky made a cameo at the end of the 1995-96 season.
Since the Blues entered the NHL, they have more regular-season wins (1,860) than all but six other teams: the Bruins (2,152), the Canadiens (2,129), the Flyers (2,013), New York Rangers (1,932), Chicago Blackhawks (1,882) and Detroit Red Wings (1,868). Each of the others has won the Cup in that span.
Only the Bruins (44) have more playoff appearances than the Blues' 42 since 1967-68, and the Blues have played more playoff games (389) than all but four other teams in that span: the Bruins (469), Canadiens (456), Flyers (433) and Blackhawks (399).